Snubbing apparatus

ABSTRACT

Snubbing apparatus for elevating and lowering an elongated tubular structure from and into a well bore while maintaining a seal between the tubular structure and the well head, wherein the tubular structure is releaseably engageable by traveling slip and traveling blowout preventer devices and by stationary slip and stationary blowout preventer devices, alternately, to elevate and lower the tubular structure, without causing movement of the tubular structure through the closed stationary blowout preventer device.

United States Patent [191 Leutwyler Mar. 19, 1974 SNUBBING APPARATUS[75] Inventor: Kurt Leutwyler, Houston, Tex.

[73] Assignee: Baker Oil Tools, Inc., Los Angeles,

Calif.

[22] Filed: May 8, 1972 [21] AppI.No.: 251,211

[52] US. Cl. 166/77 [51] Int. Cl E2lb 41/00 [58] Field of Search 166/75,77, 77.5; 173/147; 175/9 [56] References Cited UNITED STATES PATENTS1.586.923 6/1926 Townsend 166/77 1.895.132 1/1933 Minor 166/77 1.910.8905/1933 Fortune 166/77 2.555.145 5/1951 McKinney 166/77 3.665.887 5/1972Worthing l66/77 FOREIGN PATENTS OR APPLICATIONS 691.340 7/1964 Canada1616/77 Primary Examiner.lames A. Leppink Attorney. Agent, orFirm-Bernard Kriegel [57] ABSTRACT Snubbing apparatus for elevating andlowering an elongated tubular structure from and into a well bore whilemaintaining a seal between the tubular structure and the well head,wherein the tubular structure is releaseably engageable by travelingslip and traveling blowout preventer devices and by stationary slip andstationary blowout preventer devices, alternately, to elevate and lowerthe tubular structure, without causing movement of the tubular structurethrough the closed stationary blowout preventer device.

8 Claims, 6 Drawing Figures Pmmtmm m4 4 3791.570

SHEET 2 BF 3 SNUBBING APPARATUS Heretofore, snubbing apparatus or unitshave been employed for the purpose of running or retrieving tubing ordrill pipe into or from a well bore, while the well bore is maintainedunder pressure, so as to enable the well to be worked over withoutrequiring that the well be killed. This is desirable in that theproductivity of the sub-surface well zone may decline so severely afterkilling the well as to render the workover operation economicallyinfeasible.

Such snubbing operations are comparatively simple, particularly in lowpressure wells, when pulling or running flush or semi-flush joint tubingwhich has good surface quality on the outside diameter, by usingconventional snubbing apparatus including a resilient stripper whichsealingly engages the tubing to retain pressure in the well casing. Inhigher pressure snubbing operations, conventional ram type blowoutpreventers may be employed using resilient inserts on the rams forsealingly and slidingly engaging the well tubing. In either of theseevents, when the surface quality of the tubing is poor due to scale,corrosion, or the like, the stripper rubbers or ram inserts rapidlydeteriorate tending to cause loss of pressure control.

In the case that the snubbing operation involves pulling or running pipewhich has non-conformities, such as threaded couplings, or othernon-conformities, including packers, side pocket mandrels, and the like,the use of stripper rubbers is not possible, and the use of ram typeblowout preventers is necessary, so that the blowout preventer can beoperated to allow the passage of the non-conformity through thepreventer while another blowout preventer is closed on the pipe andprevents loss of pressure control, as the pipe slides through the latterblowout preventer, into the space between the respective blowoutpreventers. In such operations, the blowout preventer sealing elementsare nevertheless subject to wear and if the pipe is of poor surfacequality, the wear will be rapid and the loss of pressure controlcontinues to be a problem.

In some instances, the tubular structure or pipe to be pulled or runfrom or into the well will not permit movement of the pipe relative tothe conventional ram rype devices, for example, when the structureconsists of multiple tubing strings, single tubing strings with attachedsmall hydraulic control lines for operating subsurface valves, electriccables, or signal wires.

The present invention provides snubbing apparatus in which the mechanismfor hoisting or lowering tubular structures or pipe and a travelingblowout preventer mechanism are interconnected for unitary movementrelative to stationary pipe supporting means and stationary blowoutpreventer mechanism. The tubular structure or pipe being raised orlowered from or into the well does not slide through the blowoutpreventer means. Accordingly, the blow out preventer sealing elementsare not subject to wear, in the case'of tubing of poor surface quality,and in the case of tubular structures or pipe having non-conformities,specially designed blowout preventer sealing elements may be devised forsealing engagement with the irregular forms, since no sliding movementoccurs.

An object of the invention is to provide snubbing apparatus wherebypressure control may be maintained with certainty and wherein thesealing elements need not be replaced at frequent intervals.

More particularly, the invention contemplates a supporting structurewhich is connectable to the well head and which contains stationaryblowout preventer means adapted for sealing engagement with the tubularstructure extending through the supporting means, and a verticallyspaced traveling blowout preventer means. The supporting structure alsocarries stationary slip means engageable with the tubular structure tosupport the latter in progressive positions as it is moved from or intothe well, and a traveling slip means engages the tubular structure toshift the latter from and into the well, while the stationary slip meansare released. Actuator means are provided for shifting the travelingblowout preventer and the traveling slip means in unison.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of a formin which it may be embodied. This form is shown in the drawingsaccompanying and forming part of the present specification. It will nowbe described'in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed description is not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims.

Referring to the drawings:

FIG. 1a and lb, together, constitute a view in vertical section, showingsnubbing apparatus made in accordance with the invention, and showing awell pipe supported in the traveling slip assembly for movement from thewell and sealingly engaged by the traveling blowout preventer;

FIGS. 2a and 2!), together, constitute a view in vertical section,generally corresponding to FIGS. la and lb, but showing the well pipesupported by the stationary slip assembly in an upwardly shiftedposition, and sealingly engaged in the stationary blowout preventer;

FIG. 3 is a horizontal section, as taken on the line 33 of FIG. la; and

FIG. 4 is an enlarged vertical section, showing a typical slip assembly.

As seen in the drawings, a support structure 10 is disposed at the upperend of the well head 11 located at the top of a well into and from whicha tubular structure shown as a length of pipe P is to be run and removedby the snubbing apparatus of the invention. The pipe P is shown ashaving various non-conformities, such as a coupling 12 and a packer 13.

Included in the support structure 10 is stationary support structurecomprising a base flange 15 having a central opening 16 therethroughwhich extends through a neck 17 which carries a second, lower flange 18.The flange 18 seats on a typical blowout preventer assembly which in thepresent apparatus constitutes a stationary blowout assembly SB. Theflange I8 is connected by suitable fasteners 19 to the top of theblowout assembly SB and a suitable packing ring 20 is interposedtherebetween. The body 21 of the blowout preventer assembly SB has acentral opening 22 through which the pipe P or other tubular structureis adapted to extend and which is larger than the largest nonconformityin the pipe P which must pass through the stationary blowout preventerSB. At its lower end, the

body 21 of the stationary blowout'preventer SB seats on the top flange23 of the well head 11 and is connected to the latter by suitablefasteners 24. A packing ring seal is interposed between the blowoutpreventer body 21 and the well head flange 23.

The blowout preventer assembly SE is more or less conventional and neednot be shown in specific detail. An example of a commercially availableblowout preventer of the type shown is the type LWS double blowoutpreventer of Shaffer Tool Works, illustrated at page 4,286 of theComposite Catalog of Oilfield Equipment and Services, 1970-71. The blowout preventer SB comprises a pair of opposing upper rams 26, 26 and apair of opposing lower rams 27, 27, respectively, adapted to be actuatedbetween retracted positions, as shown in FIG. 1b, in which the rams 26and 27 clear the opening 22 through the blowout preventer body 21, andinner positions, as shown in FIG. 2b. Only the actuator means for one ofthe upper and lower rams 26 and 27 are shown in FIG. 1b, and suchactuator means comprises respective upper and lower actuator cylinders29 and 30 in which actuator pistons 31 and 32 are reciprocable. The rams26 and 27 have rods 33 and 34 extending through suitable sealing means35 into the actuator cylinders 29 and 30, and the pistons 31 and 32 aresupported on reduced rod sections 36 and 37 which extend throughsuitable seals 38 and 39. Thus, fluid under pressure may be applied tothe respective piston chambers 29 and 30 at either side of the pistons31 and 32, whereby the rams 26 and 27 are moveable between the retractedpositions of FIG. lb and the inner positions of FIG. 2b for sealingengagement with the pipe P.

For sealing engagement with the pipe P or other tubular structure, eachof the rams 26 has resilient sealing elements 26a of elastomericmaterial and the rams 27 have sealing elements 27a of elastomericmaterial. These sealing elements 260 and 27a are adaptable to seal aboutthe tubular pipe, as shown, and are also adaptable to seal about othertubular structure, such as multiple pipe strings, control lines orcables associated with one or more pipes, and the like.

- Extending upwardly from the base flange 15 of the supporting structure10 is a central tubular member 40 and a suitable number of angularlyspaced tubular cylinder bodies 41. Telescopically, shiftably extendinginto the central tubular member 40- is an elongated inner tubular member42, at theupper end of which and above the upper end of the outertubular member 40 is an outstanding flange 43, having, as seen in FIG.3, otuwardly projecting portions 44 to which the upper ends 45 of pistonrods 46 are connected by fasteners 47. These piston rods 46 extendtelescopically downwardly into tubular actuator cylinder bodies 41through an upper seal ring 48. At the lower ends of the piston rods 46are pistons 49 having piston rings 50 sealingly engaged within theactuator cylinder bodies 41. Each actuator cylinder body 41 has a baseflange 51 connected by fasteners 52 to the base flange 15 of thesupporting structure 10, a suitable packing ring 53 providing a sealtherebetween. Accordingly, in an obvious manner, pressure fluid isapplicable to the actuator cylinder body 41 at either side of the piston49 to either elevate or retract the piston rods 46 in unison, so as toelevate the supporting flange 43 or lower the latter. To provide a sealaround the telescopic tubular body 42, a packing gland 53 is threaded at54 onto the upper end of the outer tubular body 40. This confinespressure within the well head 11 to the central passage 55 through thetelescopic member 42 through which the pipe P extends and is sealinglyengageable by the blowout preventer 'rams 26 and 27 of the stationaryblowout preventer SB.

A traveling blowout preventer assembly TB is supported on the supportmember 43 so as to be vertically moveable therewith. This travelingblowout preventer assembly TB may be, for example, a single Shaffer ToolWorks type LWS blowout preventer. The body 56 of the blowout preventerTB is mounted on a support flange 57 which forms a part of the supportmember 43 by a suitable number of fasteners 58, a packing ring seal 59being interposed between the blowout preventer body 56 and the flange57.

This traveling blowout preventer assembly TB has a pair of rams 60, 60adapted to be actuated between the inner or closed positions of FIG. laand the outer retracted positions of FIG. 2a. As in the case of thestationary blowout preventer SB, each of the rams 60 has an actuator rod61 (only one of which is shown) extending through a suitable seal ring62 into an actuator cylinder 63. On a reduced end section 64 of the rod61 is a piston 65, and the rod section 64 extends through an outer seal66. Thus, the rams 60 are shiftable between the inner and retractedpositions by fluid pressure applied to either side of the piston 65, andas is typical of such blowout preventers corresponding actuator meansare provided for each of the rams 60.

Suitably supported upon the traveling blowout preventer assembly TB is atraveling slip assembly TS. in the illustrated embodiment, the travelingslip assembly TS comprises a tubular body 67 having a base flange 68connected by fasteners 68a to the top of the traveling blowout preventerTB. Removably mounted on a top flange 69 of the body 67, by fasteners70, is a plate 71 having a central opening 72. The traveling slip meansTS includes upper slip means 73 and lower slip means 74 adapted, as willbe later described, to grip the pipe P, as will be later described, toeffect upward or downward movement of the pipe string.

To the top of the actuator cylinders 41 are connected, by fasteners 75,a corresponding number of tubular posts 76, which at their upper endsare connected, by fasteners 77, beneath a work platform 78, preferablyprovided with an appropriate guard rail 79. The posts 76 arelongitudinally slotted as at 80 to receive the outwardly projectingportions 44 of the support plate 43 and thus, the support posts 76provide a shield about the actuator or piston rods 46 as the travelingblowout preventer TB and the traveling slips TS are elevated andlowered.

Mounted in an opening 81 in the work platform 78 is a stationary slipassembly SS which includes a support plate 82 corresponding to thesupport plate 71 of the traveling slip assembly TS and having an opening83. Like the traveling slip assembly TS, the stationary slip assembly SSincludes upper pipe engaging slip means 73 and lower pipe engaging slipmeans 74, as seen in FIG. 4, wherein the stationary slip means SS areillustrated as being typical.

The upper slip means 73 comprises a slip bowl 85 having an upwardly andoutwardly tapered inner surface 86, cooperative with a companion taperedsurface 87 on the pipe engaging slip elements 88 to wedge the slipsinwardly into gripping engagement with the pipe P. The slip elements 88have internal upwardly facing teeth 89 adapted to engage with the pipe Pwhen the slip elements are lowered in the slip bowl 85, the slipelements 88 releasing the pipe P when the slip elements are elevatedfrom the bowl 85. Actuator means 90 are provided for actuating the slipelements 88 to the upper or released positions from the pipe engagingpositions. Such actuator means 90 are shown as comprising actuatorcylinders 91 respectively connected at 91a to the supporting plate 82(or in the case of the traveling slip TS to the plate 71). Reciprocablein the actuator cylinder 90 is a piston 92 having its piston rod 93connected at 94 to a slip supporting arm 95. Accordingly, pressure fluidapplied to the actuator cylinders 91 is effective to elevate the slips88, but when such pressure fluid is exhausted, these slips are releasedfor downward movement to the pipe engaging positions.

The lower slip means 74 comprises slip bowl 96 having a downwardly andoutwardly tapered inner surface 97, cooperative with a companion taperedsurface 98 on the pipe engaging slip elements 99 which have in ternaldownwardly facing teeth 100 adapted to engage with the pipe P when theslip elements are elevated into the slip bowl 96, the slip elements 99releasing the pipe P when the slip elements are lowered in the bowl 96.Actuator means 101 are provided for actuating the slip elements 99 tothe lower or release position from the pipe engaging positions. Suchactuator means 101 are shown as comprising actuator cylinders 102respectively connected at 101a to the supporting plate 82. Reciprocablein each actuator cylinder 102 is a piston 104 having its piston rod 105connected at 106 to a slip supporting arm 107. Accordingly, pressurefluid applied to the actuator cylinders 102 below the pistons 104 iseffective to elevate the slips 99, but when such pressure fluid isexhausted, these slips are released for downward movement to the pipeengaging positions.

In the use of the apparatus, say for elevating the pipe string P, therams 60 of the traveling blowout preventer TB are closed to effectengagement of the sealing elements 600 with the pipe string P. Thetraveling slip means TS are operated so that the upper slips 88 areengaged in the bowl 85 to support the pipe P. At the same time, the rams26 and 27 of the stationary blowout preventer SB are retracted so thatthe sealing elements 26a and 27a clear the opening 22 through theblowout preventer body 21. Also, at the same time, the stationary slipmeans SS are operated so that the upper and lower slip means 73 and 74thereof are released from the pipe P. These conditions of operation areillustrated in FIGS. 1a and lb. Thereupon, pressure fluid is applied tothe actuator cylinders 41 below the actuator pistons 49 so as to elevateboth the traveling blowout preventer TB and the traveling slip assemblyTS to the positions of FIGS. 2 a and 2b. During such elevation, theclosed blowout preventer rams 60 prevent loss of pressure control of thewell as the pipe P moves upwardly. During the upward stroke of theapparatus, the packer 13 on the pipe P will move upwardly through thestationary blowout preventer SB to the upwardly spaced position shown infull lines in FIG. 2b. Thereupon, the rams 26 and 27 of the stationaryblowout preventer SB are closed to form a seal about the pipe P and theslip means 73 and 74 of the stationary slip means SS are actuated intoengagement with the pipe P, as shown in FIGS. 2a and 2b, to support thepipe P, so that the rams 60 of the traveling blowout preventer TB can beretracted and the slips of the traveling slip means TS opened, so thatthe traveling slips and traveling blowout preventer can be returned tothe lower postion, while the pressure in the well is retained by thestationary blowout preventer and the pipe P remains stationary.

The foregoing operation I can then be repeated to move the packer 13 inanother stroke of the apparatus further upwardly to the position shownin broken lines in FIG. 2b. The operation can be repeated to continue toelevate the pipe P. In the event that any nonconformity in the tubularstructure will not pass through the opening provided by the respectiveslip means TS and SS, they can be removed during the period that eitherthe oversize non-conformity is passing through the platform 78 or thetraveling blowout preventer TB is moving downwardly over the oversizenon-conformity.

It will also be recognized that the operations can be reversed to runthe tubular structure into the well.

I claim:

1. In snubbing apparatus for longitudinally moving an elongatedstructure extending from a well head at the top of a well: support meansincluding stationary 1 support means and vertically traveling supportmeans,

traveling slip means carried by said traveling support means within saidstationary support means and being accessible laterally through saidstationary support means, stationary slip means carried by saidstationary support means above said traveling slip means, said slipmeans respectively being selectively operable to support said elongatedstructure and to allow free movement of said elongated structuretherethrough, traveling blowout preventer means carried by saidtraveling support means, stationary blowout preventer means carried bysaid stationary support means, said blowout preventer means respectivelybeing operable to selectively form a seal with said elongated structureand to allow movement of said elongated structure therethrough, meansfor forming a seal with the well head and with the respective blowoutpreventer means when said blowout preventer means form a sea] with saidelongated structure, means releasably securing said traveling slip meansto said traveling support means, and means releasably securing saidstationary slip means to said stationary support means, wherebynon-conformities on said elongated structure can pass through saidvertical traveling support means and stationary support means uponselective removal of said traveling slip means and stationary slip meansfrom said traveling support means and stationary support means,respectively.

2. In apparatus as defined in claim 1, said means for forming a sealwith the well head comprising a tubular member connected to one of saidblowout preventer means, a tubular member connected to the other of saidblowout preventer means, said tubular members being telescopicallyengaged one within the other, sealing means between said tubularmembers, and actuator means for telescopically shifting said tubularmembers, said traveling slip means and said traveling blowout preventermeans being mounted on said traveling support means with said travelingslip means releasably secured to said traveling blowout preventer means.

3. In apparatus as defined in claim 1, said blowout preventer means eachcomprising opposed rams shiftable between retracted positions andpositions in cooperative sealing engagement with said elongatedstructure, and fluid pressure operated means for shifting said ramsbetween said positions.

4. In apparatus as defined in claim 1, said traveling slip means andsaid stationary slip means each comprising upwardly and downwardlyholding slip means operable to engage said elongated member and move thesame in both vertical directions.

5. In apparatus as defined in claim 1, said traveling slip means andsaid stationary slip means each comprising upwardly and downwardlyholding slip means operable to engage said elongated member and move thesame in both vertical directions, said blowout preventer means eachcomprising opposed rams shiftable between retracted positions andpositions in cooperative sealing engagement with said elongatedstructure, and fluid pressure operated means for shifting said ramsbetween said positions.

6. ln apparatus as defined in claim 1, said traveling slip means andsaid traveling blowout preventer means being mounted on said travelingsupport means with said traveling slip means releasably secured to saidtraveling blowout preventer means.

7. In a snubbing apparatus for longitudinally moving an elongatedstructure extending from a well head to the top of a well; support meansincluding a platform mounted in vertically spaced relation above thewell head, stationary blowout preventer means mounted on the well head,stationary slip means mounted on said platform, traveling blowoutpreventer means and inter connected traveling slip means, telescopicmeans for forming a seal with the well head and with said stationary andtraveling blowout preventer means, and actuator means interposed betweensaid stationary blowout preventer means and said traveling blowoutpreventer means for actuating said traveling blowout preventer means andinterconnected traveling slip means vertically relative to saidstationary slip means, whereby said elongated structure is adapted to bealternately moved vertically with respect to said well head and saidplatform and stationarily supported with respect to said well head andsaid platform.

8. In a snubbing apparatus as defined in claim 7, said support meanscomprising a base, post assemblies extending between said base and saidplatform in spaced relation about telescopic means, said actuator meanscomprising fluid pressure operated cylinder and piston meansincorporated in said post assemblies and connected to said travelingblowout preventer means and interconnected slip means.

1. In snubbing apparatus for longitudinally moving an elongatedstructure extending from a well head at the top of a well: support meansincluding stationary support means and vertically traveling supportmeans, traveling slip means carried by said traveling support meanswithin said stationary support means and being accessible laterallythrough said stationary support means, stationary slip means carried bysaid stationary sUpport means above said traveling slip means, said slipmeans respectively being selectively operable to support said elongatedstructure and to allow free movement of said elongated structuretherethrough, traveling blowout preventer means carried by saidtraveling support means, stationary blowout preventer means carried bysaid stationary support means, said blowout preventer means respectivelybeing operable to selectively form a seal with said elongated structureand to allow movement of said elongated structure therethrough, meansfor forming a seal with the well head and with the respective blowoutpreventer means when said blowout preventer means form a seal with saidelongated structure, means releasably securing said traveling slip meansto said traveling support means, and means releasably securing saidstationary slip means to said stationary support means, wherebynon-conformities on said elongated structure can pass through saidvertical traveling support means and stationary support means uponselective removal of said traveling slip means and stationary slip meansfrom said traveling support means and stationary support means,respectively.
 2. In apparatus as defined in claim 1, said means forforming a seal with the well head comprising a tubular member connectedto one of said blowout preventer means, a tubular member connected tothe other of said blowout preventer means, said tubular members beingtelescopically engaged one within the other, sealing means between saidtubular members, and actuator means for telescopically shifting saidtubular members, said traveling slip means and said traveling blowoutpreventer means being mounted on said traveling support means with saidtraveling slip means releasably secured to said traveling blowoutpreventer means.
 3. In apparatus as defined in claim 1, said blowoutpreventer means each comprising opposed rams shiftable between retractedpositions and positions in cooperative sealing engagement with saidelongated structure, and fluid pressure operated means for shifting saidrams between said positions.
 4. In apparatus as defined in claim 1, saidtraveling slip means and said stationary slip means each comprisingupwardly and downwardly holding slip means operable to engage saidelongated member and move the same in both vertical directions.
 5. Inapparatus as defined in claim 1, said traveling slip means and saidstationary slip means each comprising upwardly and downwardly holdingslip means operable to engage said elongated member and move the same inboth vertical directions, said blowout preventer means each comprisingopposed rams shiftable between retracted positions and positions incooperative sealing engagement with said elongated structure, and fluidpressure operated means for shifting said rams between said positions.6. In apparatus as defined in claim 1, said traveling slip means andsaid traveling blowout preventer means being mounted on said travelingsupport means with said traveling slip means releasably secured to saidtraveling blowout preventer means.
 7. In a snubbing apparatus forlongitudinally moving an elongated structure extending from a well headto the top of a well; support means including a platform mounted invertically spaced relation above the well head, stationary blowoutpreventer means mounted on the well head, stationary slip means mountedon said platform, traveling blowout preventer means and interconnectedtraveling slip means, telescopic means for forming a seal with the wellhead and with said stationary and traveling blowout preventer means, andactuator means interposed between said stationary blowout preventermeans and said traveling blowout preventer means for actuating saidtraveling blowout preventer means and interconnected traveling slipmeans vertically relative to said stationary slip means, whereby saidelongated structure is adapted to be alternately moved vertically withrespect to said well head and said platform and stationarily suppoRtedwith respect to said well head and said platform.
 8. In a snubbingapparatus as defined in claim 7, said support means comprising a base,post assemblies extending between said base and said platform in spacedrelation about telescopic means, said actuator means comprising fluidpressure operated cylinder and piston means incorporated in said postassemblies and connected to said traveling blowout preventer means andinterconnected slip means.